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International audience; Inhibition of protein–DNA interactions represents an attractive strategy to modulate essential cellular functions. We reported the synthesis of unique oligoamide-based foldamers that adopt single helical conformations and mimic the negatively charged phosphate moieties of B-DNA. These mimics alter the activity of DNA interacting enzymes used as targets for cancer treatment, such as DNA topoisomerase I, and they are cytotoxic only in the presence of a transfection agent. The aim of our study was to improve internalization and selective delivery of these highly charged molecules to cancer cells. For this purpose, we synthesized an antibody-drug conjugate (ADC) using a DNA mimic as a payload to specifically target cancer cells overexpressing HER2. We report the bioconjugation of a 16-mer DNA mimic with trastuzumab and its functional validation in breast and ovarian cancer cells expressing various levels of HER2. Binding of the ADC to HER2 increased with the expression of the receptor. The ADC was internalized into cells and was more efficient than trastuzumab at inhibiting their growth in vitro. These results provide proof of concept that it is possible to site-specifically graft high molecular weight payloads such as DNA mimics onto monoclonal antibodies to improve their selective internalization and delivery in cancer cells.

Inspired by DNA mimic proteins, we have introduced aromatic foldamers bearing phosphonate groups as synthetic mimics of the charge surface of B-DNA and competitive inhibitors of some therapeutically relevant DNA-binding enzymes: the human DNA Topoisomerase 1 (Top1) and the human HIV-1 integrase (HIV-1 IN). We now report on variants of these anionic foldamers bearing carboxylates instead of phosphonates. Several new monomers have been synthesized with protecting groups suitable for solid phase synthesis (SPS). Six hexadecaamides have been prepared using SPS. Proof of their resemblance to B-DNA was brought by the first crystal structure of one of these DNA-mimic foldamers in its polyanionic form. While some of the foldamers were found to be as active as, or even more active than, the original phosphonate oligomers, others had no activity at all or could even stimulate enzyme activity in vitro. Some foldamers were found to have differential inhibitory effects on the two enzymes. These results demonstrate a strong dependence of inhibitory activity on foldamer structure and charge distribution. They open broad avenues for the development of new classes of derivatives that could inhibit the interaction of specific proteins with their DNA target thereby influencing the cellular pathways in which they are involved. © The Author(s) 2019., Agence Nationale de la Recherche [ANR-11-BS07-013-01]; European Research Council under the European Union’s Seventh Framework Programme [ERC-2012-AdG-320892 and PEOPLE-2011-IEF-300948]; Ligue Contre Le Cancer (Comité Languedoc-Roussillon); SIRIC Montpellier Cancer [INCa Inserm DGOS 12553]; SIDACTION (AO2016, VIH2016721002). Funding for open access charge: University of Munich fund.

This work was supported by the Agence Nationale de la Recherche (project no. ANR-11-BS07-013-01 and project RETROSelect, jcjc2011 program), by the French National Research Agency against AIDS (ANRS, AO2016), by SIDACTION (AO2016, VIH20160721002), by the European Union under the Seventh Framework Programme (grant agreements nos. ERC-2012-AdG-320892 and PEOPLE-2011-IEF-300948) and by the Ligue contre le Cancer (Comité Languedoc Roussillon).; International audience; Numerous essential biomolecular processes require the recognition of DNA surface features by proteins. Molecules mimicking these features could potentially act as decoys and interfere with pharmacologically or therapeutically relevant protein–DNA interactions. Although naturally occurring DNA-mimicking proteins have been described, synthetic tunable molecules that mimic the charge surface of double-stranded DNA are not known. Here, we report the design, synthesis and structural characterization of aromatic oligoamides that fold into single helical conformations and display a double helical array of negatively charged residues in positions that match the phosphate moieties in B-DNA. These molecules were able to inhibit several enzymes possessing non-sequence-selective DNA-binding properties, including topoisomerase 1 and HIV-1 integrase, presumably through specific foldamer–protein interactions, whereas sequence-selective enzymes were not inhibited. Such modular and synthetically accessible DNA mimics provide a versatile platform to design novel inhibitors of protein–DNA interactions.

Extracellular matrix (ECM)-mimicking surfaces are pivotal tools in understanding adherent cell physiopathology. In this sense, we have recently reported on a discrete set of ECM-mimicking SAMs, among which only those exposing IGDQ peptide-alkanethiols sustain the adhesion of MDA-MB-231 cells by triggering FAK phosphorylation and peculiarly induce the migration of individual cancer cells on the subcentimeter scale. Starting from the experimentally observed relationship among the SAM composition, organization, and biological response, a systematic computational characterization aided in pinpointing the atomistic details through which specific composition and organization achieve the desired biological responsiveness. Specifically, the solvent, number and type of peptides, and presence or absence of surface fillers were accurately considered, creating representative model SAMs simulated by means of classical molecular dynamics (MD) with a view toward unravelling the experimental evidence, revealing how the conformational and structural features of these substrates dictate the specific motogenic responses. Through complementary experimental and computational investigations, it clearly emerges that there exists a distinct and precise mutual interaction among IGDQ-peptides, the surface fillers, and Au, which controls the structural properties of the ECM-mimicking SAMs and thus their motogenic potential.

Thiolated peptides bearing the Ile-Gly-Asp (IGD) motif, a highly conserved sequence of fi bronectin, are used for the preparation of anisotropic self-assembled monolayers (SAM gradients) to study the whole-population migratory behavior of metastatic breast cancer cells (MDA-MB-231 cells). Ile-Gly-Asp-Gln-(IGDQ)-exposing SAMs sustain the adhesion of MDA-MB-231 cells by triggering focal adhesion kinase phosphorylation, similarly to the analogous Gly-Arg-Gly-Asp-(GRGD)-terminating surfaces. However, the biological responses of different cell lines interfaced with the SAM gradients show that only those exposing the IGDQ sequence induce signifi cant migration of MDA-MB-231 cells. In particular, the observed migratory behavior suggests the presence of cell subpopulations associated with a “stationary” or a “migratory” phenotype, the latter determining a considerable cell migration at the sub-cm length scale. These findings are of great importance as they suggest for the first time an active role of biological surfaces exposing the IGD motif in the multicomponent orchestration of cellular signaling involved in the metastatic progression.

This review highlights the recent methods to prepare PNA-based materials through a combination of self-assembly and self-organization processes. The use of these methods allows easy and versatile preparation of structured hybrid materials showing specific recognition properties and unique physicochemical properties at the nano- and micro-scale levels displaying potential applications in several directions, ranging from sensors and microarrays to nanostructured devices for biochips.

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